The production of hydrocarbons from a tight “unconventional” formation such as tight shale/sand and siltstone/sand/carbonate often requires a hydraulic fracturing of the rock of the formation. A typical completion process involves the use of fracturing techniques in a horizontal well that are intended to “open” the formation rock above and below the well. The fracturing is intended to generate access to as much area of the hydrocarbon-bearing reservoir in the formation as possible. Optimal completion design and execution depends on a knowledge of mechanical properties of these formations.
Tight shale/sand or siltstone/sand/carbonate formations are made of sequences of layers of stiff mineral constituents in contact with layers of compliant organic and/or clay constituents. The thickness of these layers can be as large as a few feet and as thin as a fraction of an inch.
It is believed that laminated beds, occurring mainly horizontally, affect fracture growth patterns, and these effects are expressed particularly in fracture vertical height containments. See J. Miskimins and R. D. Barree, “Modeling of Hydraulic Fracture Height Containment in Laminated Sand and Shale Sequences,” SPE 80935, 2003, and D. Chuprakov and R. Prioul, “Hydraulic Fracture Height Containment by Weak Horizontal Interfaces,” SPE-173337, 2015. Arresting of hydraulic fractures at interfacial planes of weakness has also been studied and documented through laboratory studies. See Suarez-Rivera R. et al., “Understanding the effects of rock fabric on fracture complexity for improving completion design and well performance,” IPTC 17018, Beijing China, 2013.